content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.flowable.internal.operators;
  
  import org.reactivestreams.Subscriber;
  
  import io.reactivex.common.RxJavaCommonPlugins;
  import io.reactivex.common.exceptions.Exceptions;
  import io.reactivex.flowable.*;
  
  /**
   * Allows lifting operators into a chain of Publishers.
   *
   * <p>By having a concrete Publisher as lift, operator fusing can now identify
   * both the source and the operation inside it via casting, unlike the lambda version of this.
   *
   * @param <T> the upstream value type
   * @param <R> the downstream parameter type
   */
  public final class FlowableLift<R, T> extends AbstractFlowableWithUpstream<T, R> {
      /** The actual operator. */
      final FlowableOperator<? extends R, ? super T> operator;
  
      public FlowableLift(Flowable<T> source, FlowableOperator<? extends R, ? super T> operator) {
          super(source);
          this.operator = operator;
      }
  
      @Override
      public void subscribeActual(Subscriber<? super R> s) {
          try {
              Subscriber<? super T> st = operator.apply(s);
  
              if (st == null) {
                  throw new NullPointerException("Operator " + operator + " returned a null Subscriber");
              }
  
              source.subscribe(st);
          } catch (NullPointerException e) { // NOPMD
              throw e;
          } catch (Throwable e) {
              Exceptions.throwIfFatal(e);
              // can't call onError because no way to know if a Subscription has been set or not
              // can't call onSubscribe because the call might have set a Subscription already
              RxJavaCommonPlugins.onError(e);
  
              NullPointerException npe = new NullPointerException("Actually not, but can't throw other exceptions due to RS");
              npe.initCause(e);
              throw npe;
          }
      }
  }
  